Securing the Authenticity of Value Documents By Means of Characteristic Substances

ABSTRACT

The invention relates to a feature substance for securing the authenticity of documents of value, having at least one luminescent substance in particle form and nanoparticles enveloping the surfaces of the luminescent substance particles at least partially, wherein the properties of the feature substance result from the interaction of the properties of the luminescent substance and of the nanoparticles. The invention furthermore relates to a method for producing the feature substance, a method for securing the authenticity of a security element or document of value using a feature substance, as well as security elements and documents of value with authenticity features on the basis of the feature substance.

The invention relates to feature substances for securing theauthenticity of documents of value, methods for their production,security elements and documents of value containing the inventivefeature substance, as well as methods for securing the authenticity ofsecurity elements and documents of value using the inventive featuresubstance. The inventive feature substances contain both at least oneluminescent substance and at least one further substance, which ispreferably magnetic or electrically conductive.

Security elements in the sense of the present invention are elementswith authenticity features applied on or integrated in a document ofvalue for the purpose of securing authenticity. Documents of valuewithin the framework of the invention are objects such as bank notes,checks, shares, tokens, identity cards, passports, credit cards,certificates and other documents, labels, seals, and objects to besecured, such as for example CDs, packages and similar. The preferredfield of application is bank notes.

Securing the authenticity of documents of value by means of luminescentsubstances has been known for a long time. Preferably host latticesdoped with rare earth metals are used, wherein through a suitableadjustment of rare earth metal and host lattice the absorption spectrumand the emission spectrum can be varied within a large range. Also theuse of magnetic and electrically conductive materials for securingauthenticity is known per se. Magnetism, electrical conductivity andluminescence emission are machine-detectable by commercially availablemeasuring devices, luminescence in the case of emission in the visiblespectrum is also visually detectable, provided that the intensity issufficient.

The problem that the authenticity features of the documents of value arecounterfeited is practically as old as the securing of authenticity ofdocuments of value. The falsification security can for example beenhanced by not only using one feature substance, but several featuresubstances in combination, for example a luminescent substance and amagnetic substance, or a luminescent substance and a substanceinfluencing the luminescent properties.

If several feature substances are to be used in combination, the onlypossibility so far was to either produce a physical mixture of thesubstances and to apply the mixture on the surface of the document ofvalue or to integrate it in the volume of the document of value, or toapply the feature substances separately. The separate application of thefeature substances in two or more steps is time-consuming andcumbersome. Combinations of feature substances are therefore usedprimarily as mixtures. For producing the mixtures first the individualfeature substances are produced separately, then the finished featuresubstances are mixed together, usually in a dry state. In the physicalmixture thus produced the particles of the individual feature substancesare in contact with each other, but usually do not enter into anyspecific interactions with each other, i. e. the feature substances canbe separated from each other again intentionally or unintentionally. Theindividual feature substances are not associated with each other in sucha fashion that a product is created which can no longer be separatedinto its individual components.

These mixtures have the disadvantage that during their manufacturingprocess and application process a more or less strong segregation canoccur, leading to security features with differing properties, dependingon whether they were produced at the start or at the end of a batch.Frequently segregation also takes place during the storage of a mixtureof feature substances, in particular if storage takes place in the formof a dispersion, such as for example a printing ink. Consequently, ithas to be verified regularly through quality checks whether segregationor partial segregation has unintentionally led to the inhomogeneity anduselessness of the mixture.

If feature substances are provided in the shape of a certain pattern,for example form a luminescent coding, so far the only possibility hasbeen to print the feature substance or the mixture of feature substanceson the surface of a security element or of a document of value in theshape of the desired pattern, for example of the coding. A directintegration into the volume of a document of value or of a securityelement in the form of a defined arrangement, or the creation of adefined arrangement of the feature substances on the surface of adocument of value or of a security element by any methods other thanprinting has so far been impossible. In the production of codings aninhomogeneity of mixtures of feature substances caused by partialsegregation represents a particularly serious problem, since it can leadto an incorrect or unreadable coding.

It is therefore the object of the present invention to provide acombination of feature substances having at least two differentsubstances forming a non-segregating system.

The combination of feature substances is to be adapted to be providedpreferably also by methods other than printing in the shape of a patternon or in a document of value or security element.

It is also the object of the present invention to provide a method forproducing such a combination of feature substances.

It is furthermore the object of the present invention to provide amethod for securing the authenticity of a document of value or securityelement by means of such a combination of feature substances.

It is in addition the object of the present invention to provide asecurity element or a document of value having at least one authenticityfeature on the basis of such a combination of feature substances.

The solutions of the above objects result from the features of theindependent claims. Embodiments of the invention are specified in therespective dependent claims.

The inventive combination of feature substances has at least oneluminescent substance, which is excitable by radiation in the infraredand/or visible and/or ultraviolet spectrum to emit luminescence,preferably emit fluorescence. Furthermore, the inventive combination offeature substances has nanoparticles which are bound to the surfaces ofthe luminescent substance particles by adhesive forces. The adhesion issufficiently strong that during storage and processing no segregation ofthe luminescent substance and the nanoparticles takes place, at leastnot to an extent which interferes with the production of securityfeatures. Also during storage in the form of a dispersion no segregationhas to be feared.

The inventive combination of feature substances consequently representsa “composite feature substance”, which is formed by at least twodifferent substances, but behaves like one single feature substance. Theproperties of the composite feature substance represent a combination ofthe properties of the luminescent substance and the nanoparticles.Therein a “combination” can be a mere additive combination and/or aninfluencing of the properties.

The invention makes use of a phenomenon which is used similarly forstabilizing emulsions and in suspension polymerization.

In 1907 Pickering discovered that oil-water emulsions can be stabilizedby colloids that aggregate spontaneously on the interfaces of thedroplets. In the so-called “Pickering emulsions” tiny solid particlesact as emulsifiers, i. e. surfactant-free emulsion systems can beproduced. The solid particles arrange at the oil-water interface andform a dense package enveloping the droplets of the emulsion. Thissolid-particle network represents a mechanical barrier preventing thecoalescence of the droplets and thus stabilizes the emulsion.

The precondition for solid particles to act as “Pickering emulsifiers”is that the particle size is smaller than the desired droplet size by atleast factor 10, and that the solid substance is wetted by the oil phaseand the aqueous phase, but has a different affinity to the two phases.In chemical process engineering Pickering emulsifiers are used insuspension polymerization as stabilizers to prevent the stickingtogether of the growing suspension particles. The Pickering emulsifiersarrange at the interface between the suspension particles and liquidphase, envelop the suspension particles and thus prevent theircoalescence. The first precondition for the operating principle as aPickering emulsifier is that the emulsifier is insoluble in the liquidphase and is substantially smaller than the suspension particle to bestabilized. The precondition for the accumulation process in theinterface between the phases is a suitable interaction force, i. e.adhesion between the suspension particle to be stabilized and thePickering emulsifier, but simultaneously also a sufficiently goodwettability of the Pickering emulsifier by the surrounding liquid.

Surprisingly, it was now found that substances of the type of thePickering emulsifiers can under certain circumstances be used forproducing feature substances for securing the authenticity of documentsof value, wherein it is possible to obtain feature substances withproperties that could so far not be achieved.

According to the invention luminescent substance particles are envelopedby nanoparticles, wherein typically a nanoparticle monolayer is formed,in which the nanoparticles form a dense packing. However, also apartial, preferably extensive envelope can be sufficient. Theluminescent substance particles have an average particle size ofapproximately 1 to 100 μm. The volumes of the nanoparticles are smallerthan the volumes of the luminescent substance particles by at least oneorder of magnitude, preferably 2 to 3 orders of magnitude.

By enveloping a core of a luminescent substance particle bynanoparticles different feature substances become one single featuresubstance, consisting of a core and of an envelope. Consequently, theinventive feature substance is actually a system of feature substanceswhose properties result from the combination of the properties of theindividual components.

The luminescent substances usable for producing the inventive featuresubstances are not limited in any way. Generally, all substances, inparticular luminescent substances, are suitable, which can be exited toemission, in particular luminescence emission, by irradiation with lightin the infrared and/or visible and/or ultraviolet spectrum. The emissionor luminescence emission takes place preferably also in the infraredand/or visible and/or ultraviolet spectrum. The luminescent substancesare preferably fluorescent substances.

As examples for suitable luminescent substances host lattices doped withrare earth metals, for example with ytterbium, praseodymium, neodymium,etc., doped garnets or perovskites can be quoted, alsomineral-phosphorus compounds such as sulfides, oxides, selenides withtraces of heavy metals such as silver, copper, manganese or europium aresuitable. However, these examples represent mere indications and are notto be understood to be limiting in any way. Furthermore also organicluminescent substances can be used, for example rhodamines, perylenes,isoindolinones, quinophthalones and oxazinones. Methods for producingthe luminescent substances are known to the person skilled in the art.Production methods are for example described in WO 81/03508 A1. Manyluminescent substances are also commercially available, for examplePaliosecure Gelb by BASF, and Cartax by Clariant.

For forming the envelope around the luminescent substance particles inprinciple all solid substances are suitable which can be reduced tosufficiently small particles, which attach to the luminescent substanceparticles in the reduced state, i. e. as nanoparticles, and which eitherhave feature-substance properties themselves or at least modify theluminescent properties of the luminescent substance.

Substances which modify the luminescent properties of the luminescentsubstance are for example such substances which absorb in certainwavelength ranges in which the luminescent substance emits, and thuschange the luminescence spectrum. An example for such a combination isthe example 9 of the above-referenced WO 81/03508 A1 as luminescentsubstance, and nano-scale Fe₃O₄ as nanoparticle substance.

Furthermore as nanoparticles also luminescent substances can be used,thus in principle the same substances which are suitable also forforming the core of the inventive feature substance. A combination ofdifferent luminescent substances results in an overlapping luminescencespectrum.

However, preferably for the envelope of nanoparticles such substancesare used which have a machine-detectable feature differing from thedetectable feature of the core material, for example magnetic ormagnetizable substances, electrically conductive substances andsemiconductors. These substances have to be stable in the applicationmedium; for example nano-scale iron is instable in water, but afterwetting with water turns into an not strictly definable magnetic oxide(nano-scale metals are as a rule pyrophoric). When selecting thematerials it has to be kept in mind that they must not absorb stronglyin spectrums which are essential for identifying the luminescencespectrum. The luminescence spectrum must not be influenced by thenanoparticles to an interfering extent. The question of how strong achange may be so as not to be regarded as an interfering influence,essentially depends on the intended use. In some cases a change orweakening of the luminescence spectrum and/or the absorption spectrumcan actually be desirable to render an identification more difficult.

An example for a nanoparticle material are carbon nano tubes (CNTs).CNTs are microscopically small tube-shaped structures of carbon. In thewalls of the tubes the carbon is sp² hybridized and forms a honeycombstructure like in the layers of graphite. The diameter of the tubes ismostly in a range of 1 to 50 μm, but also smaller tubes can be produced.The length of the individual tubes can be up to several millimeters.Several single-walled carbon nano tubes (SWCNT) can be disposed insideeach other concentrically, so that multi-walled carbon nano tubes aregiven. Depending on the exact structure, the electrical conductivitywithin one tube can be metallic or semi-conducting.

CNTs are commercially available (e. g. from MER Corporation or NanoLabInc.) and can be reduced to the necessary dimensions by conventionalreduction procedures such as milling.

Further examples for nanoparticle materials combinable with luminescentmaterials to form inventive feature substances are nano a-iron, nanoFe₃O₄ and nano NiFe₂O₄. The feature substances with nano α-iron, nanoFe₃O₄ and with nano NiFe₂O₄ are luminescent and magnetic.

In the following some non-restrictive examples of two-componentcombinations of a luminescent substance with nano powders are listed.Example 9 of the above-referenced WO 81/03508 A1 as a luminescentsubstance, with

MWCNT (particle size 20-50 nm),

MWCNT (particle size 20-30 nm),

MWCNT (particle size 40-70 nm),

nano α-iron (APS 25 nm),

nano Fe₃O₄ (APS 20-30 nm), or

nano NiFe₂O₄ (APS 20-30 nm).

APS refers to the tube diameter of the carbon tubes. The materials arefor example available from MER Corporation.

The average particle sizes of the nano powders can be in the range ofapproximately 1 to 1000 nm, wherein the optimal particle sizes alsodepend on the size of the luminescent substance particles. Theluminescent substance particles typically have an average particle sizein a range of approximately 1 to 100 μm, and the nanoparticles aresmaller by 1, preferably 2 to 3 orders of magnitude. Preferred averageparticle sizes for the nano powders are in a range of 1 to 500 nm,particularly preferred 10 to 100 nm.

The weight ratios of luminescent substance and nano particle materialdepend on the type and the particle size of the materials. Furthermorethey depend on the exact characteristics of the desired featuresubstance, i. e. whether a feature substance is required whoseluminescent substance particles are preferably optimally surrounded by ananoparticle envelope, whether also a partial envelope is regarded assufficient, or whether, if required, also free (non-enveloped)luminescent substance particles are to be present. If a featuresubstance is desired that consists of luminescent substance particlesthat are preferably completely enveloped by nanoparticles, but does notcontain any free luminescent substance particles and no freenanoparticles, the weight ratio of the luminescent substance to the nanopowder typically lies in the range of about 1:1.

However, the weight ratios can also vary within a much larger range,approximately from 100:1 to 1:100; preferably approximately 5:1 to 1:3,in particular if the inventive feature substance contains additionalfree luminescent substances and/or nanoparticles. If such additives areused it has to be checked in prior tests, whether the resulting systemis stable against segregation.

The inventive feature substance is not limited to combinations of a typeof luminescent substance with a type of nanoparticle. Rather, two ormore different luminescent substances and/or two or more differentnanoparticles can be combined with each other. In this way it is forexample possible to obtain a luminescent substance which is alsomagnetic and electrically conductive.

The detection of the combined properties of the inventive featuresubstance takes place in the same way as the conventional detection ofthe luminescent properties, the magnetic properties and the electricallyconductive properties of the individual feature substances. The requiredspectrometers, checking devices for luminescence or magnetism andconductivity meters are commercially available.

The production of an inventive feature substance takes place in a verysimple manner, by adding the luminescent substance or the luminescentsubstances and a material in the form of a nano powder, or, if required,several different nano-powder materials, to a dispersant and mixing themfor such a time until a dispersion is obtained. The dispersion can beused as such, but preferably the feature substance is separated from thedispersion, usually by filtering, and dried.

As dispersant preferably water is used. The source materials, inparticular the nano powder, are dispersible therein only withdifficulty, but in the course of time a growing number of nanoparticlesare bound to the surfaces of the luminescent substance particles throughadhesion, and if no surplus of nanoparticles is present, finally adispersion of the feature substance is obtained, in which nonanoparticle “clusters” are contained any more. The association of thenanoparticles to the luminescent substance particles takes severalhours. The association is preferably carried out at room temperature,but the temperature can also be raised slightly, however wherein awarming only rarely results in an acceleration of the association of thenanoparticles to the luminescent substance particles. The drying of thefeature substance filtered out of the dispersion preferably takes placeat an elevated temperature, wherein the temperature depends on thechosen dispersant. If water is used as dispersant, the drying preferablytakes place at approximately 110° C.

In the case of filtration the dispersed nanoparticles are not held backby conventional standard filters. They can at best be retained byspecial filters. Thus, if a feature substance is to be produced thatconsists of luminescent substance particles whose surfaces arepreferably fully enveloped by nanoparticles, however wherein no freenanoparticles are to be present any more, production can take place in asimple manner by using a substantial surplus amount of nano powder,stirring for a sufficient time (approximately 10 hours) and subsequentlyfiltering. Nanoparticles not bound to the luminescent substanceparticles in the form of a coating, pass the filter or, depending on thedensity, float on the surface of the dispersion, whereas the featuresubstance sinks and later remains on the filter. If any nanoparticleclusters are left in the dispersion, which are also retained by thefilter, remedy is provided by careful comminuting and washing after withdispersant or prior skimming (e. g. in the case of specifically lighterMWCNTs or large-volume inclusions of air of the nano-scale oxides).

The inventive feature substances are hybrid products of the sourcecomponents both regarding their properties (luminescence, magnetism,electrical conductivity), and their appearance, such as e. g. theircolor. If for example a white or transparent luminescent substance iscoated with a black or a brown nano powder, the result is a homogeneousfeature substance power of a grey or light brown color.

The inventive feature substance is used for securing the authenticity ofdocuments of value or security elements.

Documents of value and security elements respectively consist of atleast one layer of a carrier material and possibly further layers.Furthermore they have at least one authenticity feature formed by one orseveral feature substances. In contrast to a document of value, asecurity element is not brought into circulation as such, but inconnection with a document of value, on which it is applied or in whichit is integrated.

The inventive security elements and documents of value have at least oneauthenticity feature formed by an inventive feature substance.

Regarding its possible application, the inventive feature substance doesnot differ from conventional luminescent substances. It can for examplebe integrated in the volume or in partial areas of the volume of asecurity element or document of value; wherein the carrier material canconsist of paper or plastic. Alternatively, the feature substance can beprovided in the form of a coating on at least one surface or on partialareas of at least one surface of a security element or document ofvalue.

As a further alternative the feature substance can be contained in aprinting ink, which is printed on a security element or document ofvalue. The inventive feature substance is used respectively in suchconcentrations that are usual for luminescent materials in theindividual application field, i. e. approximately 0.05 to 1 weight-%, ifthe feature substance is contained in the volume of a paper layer, andapproximately 10 to 40 weight-%, if the feature substance is containedin a printing ink.

Security elements with the inventive feature substance are preferablysecurity threads, mottling fibers, planchets or labels which areintegrated in the volume of a carrier material of a value document, orare stuck to a surface of the carrier material or a different layer of adocument of value.

To produce a security element the inventive feature substance can forexample be rubbed into a lacquer, which is then extended to form alacquer film and cut to a size fitting a security element. A suitablelacquer is a polyamide lacquer, and suitable concentrations are in arange of approximately 0.1 to 1 weight-%.

A special advantage of the inventive feature substances becomes obviousif an inventive feature substance is to be provided in a defineddistribution, if the feature substance is to form a code for example. Insuch a code, areas with a high concentration of the feature substancealternate in a predetermined manner with areas with a lowerconcentration of the feature substance, or completely without thefeature substance. The arrangement of the areas with a highconcentration of the feature substance and with a low concentration ofthe feature substance (or without the feature substance) ismachine-readable. So far such codes could be produced only by printingluminescent substances in a certain pattern. They could not be formeddirectly in the volume of a document of value.

However, the inventive feature substances have the specialcharacteristic that they do not only have luminescent features, but thatthey are preferably also magnetic or magnetizable or electricallyconductive. In an electrical or magnetic field the nanoparticles of theenvelope of the luminescent substance particles align with the field,and the feature substance has the tendency to migrate within this field.The precondition for such an alignment and possibly migration is thatthe surrounding medium of the feature substance is sufficiently liquidin order to allow a movement of the feature substance. In practice thismeans that the inventive feature substance can be oriented or moved in adesired manner within a carrier material or a printing ink by applying asuitable magnetic or electrical field, as long as the carrier materialis still sufficiently soft or wet, or the printing ink is stillsufficiently liquid. A pattern of areas with a high concentration of thefeature substance and areas with a low concentration of the featuresubstance in a paper layer can for example be produced in that aninventive feature substance with luminescent and magnetic properties isintegrated in the humid paper in the paper machine, while an arrangementof magnets in the desired code pattern is arranged at the paper. Themagnetic nanoparticles of the feature substance then orient themselvesin the humid paper mass, and the feature substance particles migratetoward the magnets, whereby they reproduce the arrangement pattern ofthe magnets, thus the code. The code can be read out e. g.spectrometrically.

In the following a general production procedure for an inventive featuresubstance is specified.

2 g of the above-mentioned example 9 of WO 81/03508 A1, and 1.5 g MWCNTnano powder are weighed out into a beaker with approximately 50 ml waterand are stirred at room temperature for one day. At the beginning of themixing process the nano powder floats on top and partly forms bigclusters. Once the hardly dispersible nano powder is finely dispersed inthe dispersion thus produced, the material is filtered. The nanomaterial does not penetrate the filter through the filter pores. Thefiltered material is dried at 110° C. for example over night.

Subsequently, the thus obtained material can for example be integratedin the production of bank note paper, e. g. at a dosage of 0.4 weight-%.

Likewise the material can be rubbed into a polyamide lacquer and thelacquer can be extended to form a lacquer film, wherein theconcentration of the feature substance also amounts to 0.4 weight-% forexample. The lacquer film is suitable for sticking onto bank notes.

The authenticity of the bank note can now be verified both by measuringthe infrared luminescence and by measuring the electrical conductivitydetermined by the nano powder. Of course the authenticity can also beestablished by measuring both features.

Instead of the example specified, also the nano powders mentioned abovein connection with WO 81/03508 A1 can be used. Likewise, otherluminescent substances can be used.

1. A feature substance for securing the authenticity of documents ofvalue, comprising at least one luminescent substance in particle formexcitable by radiation in at least one of the infrared visible andultraviolet spectrum to emit luminescence, comprising nanoparticlesenveloping the surfaces of the luminescent substance particles at leastpartially, wherein properties of the feature substance result from theinteraction of the luminescence emission properties of the luminescentsubstance and properties of the nanoparticles.
 2. The feature substanceaccording to claim 1, wherein the luminescent substance emits in atleast one of the infrared, visible and ultraviolet spectrum.
 3. Thefeature substance according to claim 1, wherein the luminescentsubstance particles are enveloped substantially completely bysubstantially a monolayer of nanoparticles.
 4. A method according toclaim 1, wherein the luminescent substance is selected from luminescentsubstances on the basis of host lattices doped with at least one rareearth metal.
 5. The feature substance according to claim 1, wherein theluminescent substance is selected from the mineral-phosphorus compounds.6. The feature substance according to claim 1, wherein the luminescentsubstance is selected from organic luminescent substances.
 7. Thefeature substance according to claim 1, wherein the luminescentsubstance is present in the form of particles with an average particlesize in the range of 1 to 100 μm.
 8. The feature substance according toclaim 1, wherein the nanoparticles are selected from the groupconsisting of magnetic materials, magnetizable materials, electricallyconductive materials, semiconductor materials and mixtures thereof. 9.The feature substance according to claim 1, wherein the nanoparticlesare selected from the group consisting of carbon nano tubes, nanoα-iron, nano Fe₃O₄, nano NiFe₂O₄ and mixtures thereof.
 10. The featuresubstance according to claim 1, wherein the nanoparticles have anaverage particle size in the range of 1 to 1000 nm.
 11. The featuresubstance according to claim 1, wherein the weight ratio of luminescentsubstance particles to nanoparticles is in the range of 10:1 to 1:10.12. The feature substance according to claim 1, including luminescentsubstance particles that are not enveloped by either or bothnanoparticles, and free nanoparticles.
 13. The feature substanceaccording to claim 1, including either or both at least two differentluminescent substances and at least two different types ofnanoparticles.
 14. A method for producing a feature substance as definedin claim 1, comprising adding at least one luminescent substance inparticle form and at least one substance in the form of a nano powder toa dispersant and stirring the mixture for such a time until a dispersionis obtained.
 15. The method according to claim 14, wherein thedispersion is filtered to separate the feature substance.
 16. The methodaccording to claim 15, wherein the separated feature substance is dried.17. The method according to claim 14, wherein as dispersant water isused.
 18. The method according to claim 14, wherein the featuresubstance is mixed with either or both at least one further featuresubstance and/or and at least one further type of nanoparticles.
 19. Amethod for securing the authenticity of a security element or documentof value, comprising: applying a feature substance as defined in claim1, on at least partial areas of at least one surface of the securityelement or document of value, or integrating a feature substance asdefined in claim 1, in at least one partial area of the volume of thedocument of value or security element.
 20. The method according to claim19, wherein the security element or document of value is subjected toelectrical or magnetic fields during the application or integration ofthe feature substance in such a fashion that an orientation and, ifdesired, a migration of the feature substance particles within theelectrical or magnetic field takes place.
 21. The method according toclaim 20, the migration leads to a defined distribution of the featuresubstance particles that is machine-verifiable or visually verifiable.22. The method according to claim 21, wherein the defined distributionforms a code.
 23. A document of value or security element comprising atleast one carrier material and, on or within the carrier material, atleast one authenticity feature based on a feature substance, wherein thefeature substance is a substance as defined in claim
 1. 24. The documentof value or security element according to claim 23, wherein the carriermaterial comprises paper or plastic.
 25. The document of value orsecurity element according to claim 23, wherein the feature substance isprovided in the volume of the carrier material.
 26. The document ofvalue or security element according to claim 23, wherein the featuresubstance is present in a layer applied on at least partial areas of asurface of the carrier material.
 27. The document of value or securityelement according to claim 23, wherein the feature substance is presentin a printing ink applied on a surface of the document of value orsecurity element.
 28. The document of value or security elementaccording to claim 23, wherein the feature substance shows a defineddistribution which is visually verifiable or machine-verifiable.
 29. Thedocument of value or security element according to claim 28, wherein thedefined distribution forms a code.
 30. The security element according toclaim 23, having a configuration of at least one of a security thread,mottling fiber, planchet or label.
 31. The document of value accordingto claim 23, including a security element according to claim 23.